Over a ten-day period, the youngster from Lancashire sent thousands of instant messages to 18-year-old Sevdet Besim, who shared his admiration for the Islamic terror group, the Old Bailey heard.
Police examined his mobile phone and uncovered the exchanges after he was arrested on 2 April in the Blackburn area.
In one message on 18 March, the boy, who was 14 at the time, said: “Suggest you break into someone’s house and get your first taste of beheading.”
Besim replied that it seemed “a little risky”.
Yesterday the smartly-dressed, bespectacled British youngster pleaded guilty to inciting terrorism via videolink from Manchester Crown Court.
The charge states that between 15 March and 26 March 2015 he “incited a person to commit an act of terrorism wholly or partly outside the UK, namely the murder of police officers during an attack on a parade to commemorate Anzac Day in Australia”.
A second charge of inciting terrorism overseas in relation to beheading a person in Australia was dropped.
Outlining the case, prosecutor Paul Greaney QC said: “The defendant has now pleaded guilty to what was count one on the indictment. This charge represents his conduct over 10 days in March 2015 in inciting an Australia-based man named Sevdet Besim to commit an act of terrorism abroad, namely the murder of police officers during an attack upon a parade to commemorate Anzac Day in Melbourne.
“The evidence of this plot derives from literally thousands of instant messages between the defendant and Sevdet Besim recovered from the defendant’s mobile telephone.
“Those messages reveal the intentions of the plotters and their targets, along with their motivation which may be summarised as support for Isis and their enthusiasm for the attack.
“The messages also set out the plotters’ preparations for the attack. On the 18th March 2015, as part of those preparations, the defendant sent Sevdet Besim a message that read, ‘Suggest you break into someone’s house and get your first taste of beheading’.
“Sevdet Besim responded to say that this seemed ‘a little risky’ and that aspect of the preparations appears then to have drifted away.”
This exchange was the subject of count two on the indictment but Mr Greaney said it had been deleted because the prosecution was happy to deal with it as “part and parcel” of the offence in count one.
Mr Justice Saunders ordered pre-sentence reports to find out if there was any “indoctrination” as he adjourned the case for sentencing at Manchester Crown Court. He said: “I want some assessment of how and why it occurred.”